Field of the Disclosure
The present invention relates to digital display devices, and more particularly to method and device for tuning a color temperature in a digital display device, in which variation of color temperatures and color feelings between gradients is reduced for improving a picture quality.
Discussion of the Related Art
Currently, as the digital display device, a liquid crystal display device LCD or an organic light emitting diode OLED display device is used, mostly.
The liquid crystal display device displays an image by using electric and optical characteristics of liquid crystals having anisotropy in refractive index and dielectric, wherein each of pixels of a pixel matrix produces a gradation by controlling transmissivity of a light transmitting a polarizing plate by varying orientation of the liquid crystals in response to a data signal.
The organic light emitting diode display device, a spontaneous emissive device which makes an organic luminescence layer to emit a light by re-combination of an electron and a hole, has advantages in that brightness is high, a driving voltage is low, and production of very thin device is possible. The organic light emitting diode display device produces the gradient as a pixel driving circuit controls intensity of a current being supplied to the organic light emitting diode in response to the data signal.
In general, a standard color temperature of the digital display device is set to be 6500K±500K, and a user can maintain the same color feeling only when the color temperature of each gradient is consistent. However, since a related art liquid crystal display device has a great variation of the color temperatures between the gradients, the liquid crystal display device has a problem in that a picture quality becomes poor due to a color feeling difference between the gradients.
Referring to FIG. 1, it can be known that the related art liquid crystal display device has a variation of color temperatures between the gradients in a range of ±2700K with reference to a reference color temperature of 6500K. The higher the color temperature with reference to 6500K, white appears bluish, and the lower the color temperature with reference to 6500K, white appears reddish. The related art liquid crystal display device has a problem in that the great variation of color feeling between the gradients caused by the color temperature variation makes the picture quality poor.
In order to solve this problem, in the related art liquid crystal display device, a designer tunes a digital gamma algorithm DGA of each of red, green and blue to tune the color temperature. However, since the related art color temperature tuning depends on a designer's sense, the related art color temperature tuning has problems in that, not only quantitative evaluation is difficulty, a long time period is required for dealing with a buyer's standard, but also reduction of the color temperature variation to be below ±2400K with reference to 6500K is difficult even if the color temperature tuning is made.
The problems caused by the variation of color temperatures between the gradients takes place not only to the liquid crystal display device, but also to the organic light emitting diode display device.